1. Field of the Invention
Applicant's invention relates to surgical instruments and, more particularly, to trocars. Trocars are used to pierce or puncture an anatomical cavity to provide communication with the inside of the cavity during a surgical procedure.
2. Background Information
Endoscopic surgery, particularly laparoscopic surgery, is currently becoming a significant method for performing surgeries. It is projected that by the year, 2000 half of all surgical procedures will be performed endoscopically. Laparoscopic surgery has become the surgical procedure of choice because of its patient care advantages over "open surgery."
For the past several decades, endoscopic surgery has been available as a method of diagnosis and, for a very limited number of disorders, a treatment. Until recently, a factor limiting the types of surgeries that could be performed laparoscopically was the ability to employ intraoperative assistance. In the past, endoscopes allowed only direct visualization by the surgeon, such as the endoscope disclosed in U.S. Pat. No. 4,254,762 issued to Yoon. This led to the situation where the surgeon had one hand holding the laparoscope to his eye and then had only one hand available to operate.
Fortunately, miniaturization of video camera computer chips has led to the development of video cameras that can easily be attached to an endoscope or laparoscope. During surgery, connecting a video camera and monitor to the laparoscope enables all the operating room personnel to view the surgical procedure, rather than just the surgeon. Thus, the operating room personnel are able to provide operative assistance just as they do with open surgery. The type and number of surgical procedures amenable to laparoscopic surgery is presently one of the most rapidly developing areas of medicine.
The pivotal advantage of laparoscopic surgery over open surgery is the decreased post-operative recovery time. In many instances, a patient is able to leave the hospital within twenty four hours after laparoscopic surgery has been performed. This is compared to a five day to ten day hospitalization necessary to recover from an open surgical procedure. Additionally, laparoscopic surgery provides a decreased incidence of post-operative abdominal adhesions and decreased post-operative pain with enhanced cosmetic results.
An essential medical instrument for endoscopic procedures is the trocar. Trocars are sharp, pointed surgical instruments used to puncture the wall of an anatomical cavity. The trocar consists of a tube or cannula and a cutting element called an obturator or stylet. The obturator fits within the cannula and has a sharp piercing tip at its end.
A conventional laparoscopic trocar insertion procedure usually follows insufflation of the abdominal cavity with CO.sub.2 gas. The introduction of CO.sub.2 gas into the abdominal cavity lifts the abdominal wall away from the internal viscera. Once this is done, the abdominal wall is penetrated with the trocar. After insertion of the trocar through the abdominal wall, the surgeon removes the obturator leaving the cannula or tube protruding through the body wall. A laparoscope or laparoscopic instruments can then be inserted through the cannula to view internal organs or perform surgical procedures.
Penetrating the wall of the abdominal cavity with the trocar is done quickly. The sharp point of the obturator encounters great resistance from the skin, muscle, and tissue membranes of the abdominal wall while it is being pushed through these structures. Once the trocar's sharp point and blade pass through the abdominal wall and into the cavity, the resistance to the trocar drops quickly. Unless the surgeon immediately stops pushing the trocar just as soon as penetration of the abdominal wall is complete, there is a chance that the trocar will penetrate further into the abdominal cavity and injure internal organs.
Within the abdominal cavity, the obturator's sharp point could easily injure or cut an internal organ upon the slightest contact. If an internal organ is inadvertently injured or cut, unless immediate and massive hemorrhage occurs, the injury may not become apparent until long after completion of the surgery. At a minimum, such an injury will delay a patient's recovery and, more likely, could seriously endanger the patient's health. Additional corrective surgery on an open basis may be required, subjecting the patient to additional risks and costs.
Prior to 1987, the only trocars available for laparoscopic use were instruments made from stainless steel, such as those disclosed in U.S. Pat. No. 3,994,287 issued to Turp et al., and U.S. Pat. No. 3,613,684 issued to Sheridan. A problem common to all of these "classic" trocars is that they do not have a safety shield which covers the sharp, cutting tip of the obturator once it pierces the cavity wall.
Several changes and additions have been made on the functional design of these classic trocars. The most significant improvement on the classic trocar is the addition of a spring-loaded safety shield that snaps forward to cover the sharp point and blade of the obturator once the trocar has penetrated the abdominal wall, such as those disclosed in U.S. Pat. No. 4,601,710 issued to Moll, U.S. Pat. No. 4,654,030 issued to Moll et al. and U.S. Pat. No. 4,535,773 issued to Yoon. In these devices, the safety shield is a plastic sleeve which is positioned concentrically about the obturator. Because of this safety feature, trocars with a spring loaded safety shield have become the most used trocars in laparoscopic surgery.
However, these spring loaded safety shields have cumbersome safety shield control mechanisms which are difficult to tell if the safety shield is armed or engaged. To be sure of the safety shield's operation, a surgeon will need to verify the proper operation of the safety shield prior to use. Since the safety shields are mounted to the obturator, surgeons are required to test the safety shield's operation with the obturator in place by manually pressing the safety shield of the trocar. Unfortunately, this results in many slight puncture wounds being experienced by the surgeons as they are attempting to verify the safety shield's operation.
Currently, laparoscopic trocars with the spring loaded safety shields are manufactured only as a thin wall plastic disposable instruments. These light weight plastic instruments are used once and then discarded as medical waste, adding significantly to the already escalating health care costs. For example, the single use disposable plastic trocars cost approximately sixty five dollars to ninety dollars each. Usually two to four trocars are used for each laparoscopic procedure. Thus, surgical costs are unnecessarily increased about two hundred dollars to three hundred and fifty dollars per laparoscopic procedure, as well as adding to the overbearing problem of medical waste by the use of these disposable trocars. Presently, however, the increased health care cost has been unavoidable because the only safety shielded trocar available was a disposable item. No one had invented a easily disassembled, easily cleaned, sterilized, and easily reassembled for reuse, safety shielded trocar.